Double-shot depth-resolved displacement field measurement using phase-contrast spectral optical coherence tomography

Area of Science:

• Biomedical Optics
• Optical Metrology
• Materials Science

Background:

• Sub-surface displacement measurement is crucial for understanding material deformation and biological tissue mechanics.
• Existing techniques often lack the sensitivity, speed, or non-contact capabilities required for dynamic or scattering samples.
• Optical Coherence Tomography (OCT) offers high resolution but phase contrast methods are needed for precise displacement quantification.

Purpose of the Study:

• To develop and validate a phase contrast spectral OCT system for high-sensitivity sub-surface displacement mapping.
• To demonstrate the system's capability for analyzing dynamic deformations in scattering media.
• To assess the system's performance in a biological tissue application (porcine cornea).

Main Methods:

• Implementation of a phase contrast spectral OCT system using low-cost components.
• Acquisition of displacement maps within a 2-D slice of the sample in a single image.
• Validation using well-controlled geometries (tilting glass sheets) and standard two-beam interferometry.
• Application to measure through-the-thickness phase changes in a porcine cornea under simulated intraocular pressure.

Main Results:

• The system achieves a displacement sensitivity of approximately 10 nm.
• Sub-surface displacement fields were successfully mapped in scattering media.
• The system demonstrated potential for mapping displacements in moving targets.
• Phase changes in porcine cornea correlated with applied pressure were measured.

Conclusions:

• Phase contrast spectral OCT is a viable technique for sensitive, non-contact sub-surface displacement mapping.
• The developed system offers a cost-effective solution for analyzing static and dynamic deformations.
• This technology has potential applications in biomechanics, non-destructive testing, and medical diagnostics.